623 © 2012 Triveni Enterprises J. Environ. Biol. Vikas Nagar, Lucknow, INDIA 33, 623-628 (2012) [email protected] ISSN: 0254-8704 Full paper available on: www.jeb.co.in CODEN: JEBIDP Hatchery production of the clownfish Amphiprion nigripes at Agatti island, Lakshadweep, India Author Details T.T. Ajith Kumar Centre for Marine Living Resources and Ecology - Field Research Station, Agatti Island - 682 553, Lakshadweep, India (Corresponding author ) e-mail : [email protected] M. Gopi Centre for Marine Living Resources and Ecology - Field Research Station, Agatti Island - 682 553, Lakshadweep, India K.V. Dhaneesh Centre for Marine Living Resources and Ecology - Field Research Station, Agatti Island - 682 553, Lakshadweep, India R. Vinoth Centre for Marine Living Resources and Ecology - Field Research Station, Agatti Island - 682 553, Lakshadweep, India S. Ghosh Centre for Marine Living Resources and Ecology - Field Research Station, Agatti Island - 682 553, Lakshadweep, India T. Balasubramanian Centre for Marine Living Resources and Ecology - Field Research Station, Agatti Island - 682 553, Lakshadweep, India T. Shunmugaraj Centre for Marine Living Resources and Ecology - Field Research Station, Agatti Island - 682 553, Lakshadweep, India Abstract Healthy individuals of matured clownfish, Amphiprion nigripes and sea anemone, Heteractis magnifica were Publication Data collected from the Agatti island lagoon by snorkeling. During ‘conditioning’ for 3 months, pair formation occurred and the same were transferred to rectangular fiber glass spawning tanks of 1000 l capacity. Suitable water Paper received: quality parameters were maintained. The fishes were fed with tuna eggs, boiled clam meat, squid, octopus and 11 November 2010 trash fish thrice in a day. Reproductive behaviour and embryonic development were documented. Spawning took place in between 0900 - 1100 hr and hatched-out occurs, after sunset following an incubation period of Revised received: 8-9 days. Size of the newly laid egg was 2.0-2.2 mm in length and 1.0-1.2 mm in width. The larval rearing 05 May 2011 tanks were maintained with UV-treated water and followed the optimal physico-chemical parameters as in the parent tanks. The different light regimes and diets were used for the successful larval rearing. The maximum Accepted: larval survival (61%) was achieved at the photoperiod of 24 L/0D. Within 15-17 days, the larvae metamorphosed 26 May 2011 and took up parent colouration and comparatively high growth rate was observed when fed on algae enriched rotifer than those with poly unsaturated fatty acid (PUFA). Key words Hatchery production, Amphiprion nigripes , Embryonic development, Larval rearing, Photoperiod Introduction year 2007, the global trade on ‘marine and fresh water fishes and invertebrates’ were valued at US$ 327 million. The global Tropical and subtropical countries are among the world’s demand for aquarium fish has been estimated to worth US$ largest exporters of marine ornamental species for the aquarium 200-330 million yr -1 (Wabnitz et al ., 2003), of this, the annual trade (Olivotto et al ., 2003). Due to the increasing demand, global trade ranged between 11 and 12 million coral fishes, many studies on ornamental fishes, particularly, larval rearing clearly indicating the need of hatchery production of coral fishes and nutrition have been performed (Avella et al ., 2007). In the like clownfishes. Journal of Environmental Biology May 2012 624 Kumar et al. In India, Lakshadweep has rich marine ornamental fish diversity. 30 min after feeding. Approximately 50% of water was The complex interaction of mega, meio and micro-fauna makes exchanged weekly once. Lakshadweep as an example of coral reef ecosystem (Murty et al ., Behavioural observations: Courtship behaviour and spawning 2002). Agatti island is part of the Chagos-Maldives-Lakshadweep activities were monitored daily (0900-1000, 1300-1400 and 1700- archipelago, which is the largest atoll system in the world (Jones, 1800 hrs). The fishes used to lay eggs at morning hours. The 1986). As many as 29 species of clownfishes and 10 species of fecundity varied from 300 to 700 eggs and the incubation period symbiotic sea anemones reported worldwide (Allen et al ., 2008), was 8 to 9 days. The eggs were tended and guarded by the male. among them, the Maldives clownfish, Amphiprion nigripes is restricted The area (A) of the nest was calculated by a constant factor 3.14 to Maldive and Lakshadweep islands. with minimum and maximum radius of nest as proposed by Robertson Protandrous sex change is a peculiar feature of the et al. (1988) modified by Hoff (1996). The total number of eggs was clownfishes. They are born as male and dominant member of the estimated by counting the number of eggs per cm 2 and multiplying group changes sex to female and the second largest sub-adult then with deposition area. becomes the functioning male (Wood and Aw, 2002). At present, Preparation of algal enriched rotifer diet: The algal stock natural population of clownfishes is declining due to overexploitation culture ( Nannochloropsis spp. and Chlorella spp) was maintained to meet the burgeoning demand in aquarium trade. Incidentally, A. using F2 medium and outdoor mass culture by commercial fertilizers. nigripes survives longer in aquarium, has more attractive body Rotifer, Brachionus plicatilis was mixed with algae and mild aeration coloration and fetches a higher price in the global market. Several was provided for enrichment and after one hour they were filtered attempts have been made to replenish the clownfish population by using plankton net and used as larvae feed. mass-producing them (Ajith Kumar and Balasubramanian, 2009). In the present study, breeding, embryonic development, mass scale Embryonic development: A total number of 5 eggs were sampled larval rearing and experiments on influence of photoperiod and diet randomly at each sampling to study the embryonic development. on larval growth and survival were carried out from the The sampling was started immediately after completing the spawning Lakshadweep, the coral paradise of the Arabian sea. until hatch out. The eggs were transferred into sterile plate with UV- filtered seawater. Time was recorded when 50% of the collected Materials and Methods embryos attained the stages such as cleavage, blastulation, Fish collection: Fourteen numbers of clownfish, A. nigripes (total gastrulation, organogenesis, embryo, pre-hatching and larval stage length 6.5 ± 5 cm) and seven sea anemone, Heteractics magnifica clearly. The main morphological and functional features of each were collected using snorkeling at a depth of 1 to 2 m at different developmental stage were recorded by light microscope (Motic, locations of Agatti lagoon (Lat. 10º 51’N, Long. 72º 11’E) during B1-series Biological Microscope) and digital camera (Canon, April, 2009. They were accommodated in 100 l capacity cylindrical China). fibre glass tank, fitted with battery aerator and transferred to the Larvae rearing: The eggs hatched out after sunset and occasionally hatchery at Agatti island. Subsequently, the fishes and anemones it extended to night (1900 to 2300 hrs). After completion of hatching, were introduced into a 3000 l tank for quarantine. the floating larvae were gently collected by glass bowl and transferred After one month period, ten healthy fish and five sea to previously set larval rearing tank. Cylindrical white coloured anemones were shifted to the conditioning tank. Pair formation fibre glass tanks (100 l capacity) were used for larval rearing. Prior occurred during three month period of conditioning and the to larvae transfer, the tanks were filled with 20 l treated seawater paired fish were transferred to separate 1000 l capacity fibre and 5 l algae to “green up” the system. A 15 W white fluorescent glass tank. The bio-filtered water was used for the brooder bulb was fixed on top of the tank for illumination. After stocking the -1 tanks. Water quality parameters such as temperature (26±2ºC) larvae (3 nos. l ), approximately 10% water exchange was made was measured by mercury centigrade thermometer with 0.5ºC every day. The newly hatched larvae were divided into groups to accuracy, salinity (34-35 psu) by salinity meter (Ecoscan, study the effect of photoperiod and suitability of diets on survival and st Singapore), pH (8.0-8.3) by pH pen (Eutech, Singapore), growth. Three numbers of larvae were randomly collected on 1 , th th th dissolved oxygen (5-6.5 mgl -1 ) by D.O probe (Ecoscan, 5 , 10 and 15 day after hatch to measure the total length and Singapore), ammonia (less than 0.01 ppm) by ammonium test mouth gap in nearest millimeter by ocular micrometer (Erma, Tokyo) kit (Merck, Germany). The photoperiod was maintained at 13 hr and light microscope. light: 11 hr dark by 25 W fluorescent bulbs. Ceramic tiles and The larvae from same parents were stocked in different live rocks were provided as substratum for egg laying. The fish experimental tanks with three modes of photoperiod as well as were fed with tuna egg mass, boiled clam meat, squid and three different feeds. The larvae were divided into five groups (A- octopus, thrice a day (0800, 1200 and 1600 hr) at 4% of the control, B1, B2, C1 and C2) and stocked them as 100 larvae per body weight, and the sea anemones were fed with fresh shrimp. tank. The feeding schedule was commenced after 7 hrs of hatched Uneaten food particles and excreta were removed by siphoning out and fed 4 times in a day. Journal of Environmental Biology May 2012 Hatchery production of clownfish at Agatti island 625 The experimental tank B1 was maintained with algal Statistical analyse : Statistical analyses were done with the enriched rotifer and 16L/8D photoperiod, and B2 retained with poly software STATISTICA. The results were analyzed using analysis unsaturated fatty acid (PUFA) enriched rotifer and 16L/8D of variance (ANOVA) with different variables namely survival and photoperiod. While, the tank C1 was maintained with algal enriched growth.